Great blue lobelia, or Lobelia siphilitica is a lovely plant in late fall, when plants with yellow flowers are usually prominent, according to Helen Hamilton, past president of the John Clayton, Virginia Native Plant Society, in southeastern Virginia.

Tall spikes of brilliant true-blue flowers grow on a stiff, unbranched, leafy stalk, 1-3 feet high. Flowers of this genusall have 2 narrow lobes or “ears” above, with 3 wider lobes forming a lip below. The 1-inch long violet-blue flowers of Great Blue Lobelia are striped with white on the 3 lower lobes, which appear more prominent than the lobes above. Leaves are alternate on the stem, finely toothed and pointed.

Great Blue Lobelia is a wetland native species, requiring wet to moist soil, fertile and loamy. The plant requires little maintenance, growing in part shade, but in full sun the soil must be consistently moist, as in rain gardens. The natural habitat is meadows, moist thickets and swamps from Maine to Manitoba and Colorado, south to North Carolina and Texas. While found in most counties of Virginia, it is infrequent in the Coastal Plain.

This clump-forming perennial blooms July through October, may self-seed in optimum growing conditions, and can be divided in the spring. Also known as Blue Cardinal Flower, this plant tolerates drier conditions than the red species.

Early medical writers thought American Indians used the root primarily to treat syphilis, hence the species name siphilitica. While potentially poisonous, the American Indians used root tea for syphilis, and leaf tea for a number of illnesses, such as colds, worms, nosebleeds, coughs and headaches.